There's a little more to it than the dimensions, but if you just want it to work (ignoring the feel), then it's not too hard to find a replacement. If you have the part number off the original, you might be able to find a spec sheet online somewhere. Different switches have different actuation forces as well as a different MTBF.
I have some LS-30's that one switch failed on. I couldn't find the exact same switch, but I spoke to Mouser or DigiKey (can't remember which) and they worked with me to find a replacement of the same specs.
Oh, one more thing. If you can't find a lever arm that's exactly the right length, you can always get one that's a bit longer and cut it to the right dimensions.
Good luck!